The invention relates to apparatus for the processing of used spot welding electrodes. More especially, the invention concerns such apparatus which comprises a press including a forming tool having a punch whose head and shape corresponds to a blind bore in the spot welding electrode, the punch being mounted so as to float laterally about a clearance corresponding to a maximum eccentricity of the blind bore with respect to an external shape of a used spot welding electrode. The press also contains a die having a recess which corresponds to the desired external electrode shape.